There is a vertical substrate processing apparatus as a substrate processing apparatus that performs substrate processing in a process of manufacturing a semiconductor device. In the vertical substrate processing apparatus, a plurality of substrates are stacked and held in multiple stages, loaded into a process chamber, and processed at once.
During the processing, a furnace port at the lower portion of the process chamber can be the coldest in the process chamber. When a precursor gas diffuses to the furnace port, reaction by-products of the precursor gas adhere to the furnace port, which may cause a generation of particles. There has been conventionally proposed a substrate processing apparatus that supplies a purge gas to a furnace port having a high process gas concentration so as to suppress adhesion of by-products to metal parts.
However, in some types of substrate processing apparatuses, a dilution of the precursor gas is insufficient due to a configuration of the furnace port, and by-products by the precursor gas may adhere to the furnace port. In particular, when metal parts are used in the furnace port, by-products tend to adhere to the metal parts. For this reason, even as cleanings are performed more frequently, particles may be generated.